Nasal ventilation is an important factor in evaluating the diagnostic value of nasal nitric oxide in allergic...

The role of nasal nitric oxide (NO) in the diagnosis of allergic rhinitis (AR) is controversial. The aim of this study was to identify factors that may affect levels of nasal NO in AR patients and evaluate the role of nasal NO in the diagnosis of AR.

Seventy-five AR patients and 31 healthy controls were enrolled in this study. AR symptom scores were assessed using the visual analog scale. Eosinophil cationic protein (ECP) was detected by enzyme-linked immunoassay, nasal NO was measured using a chemiluminescence analyzer, and nasal airway resistance (NAR) was assessed by active anterior rhinomanometry.

Nasal obstruction score, ECP, and NAR were found to be independently associated with nasal NO. Nasal NO level in patients with nasal obstruction score <7 (mild-to-moderate obstruction) was significantly increased compared with healthy subjects (282.1 ± 122.6 vs 150.7 ± 48.4 ppb; p < 0.001), and significantly decreased in patients with nasal obstruction score ≥7 (severe obstruction) (97.2 ± 52.2 vs 150.7 ± 48.4 ppb; p < 0.001). Nasal NO and ECP in secretion were positively correlated in patients with mild-to-moderate nasal obstruction (r = 0.678), but not in patients with severe nasal obstruction (r = 0.077). In patients with NAR <0.65 Pa/cm³ /s, the correlation coefficient was highest between NO and ECP (r = 0.685). The areas under the receiver operating characteristic curve for nasal NO level were 0.878 and 0.939 in patients with nasal obstruction scores <7 and NAR <0.65 Pa/cm³ /s, respectively.

Nasal patency affects nasal NO level significantly, and may reflect the severity of nasal inflammation in AR patients with mild-to-moderate nasal obstruction, but not in patients with severe nasal obstruction.